Mold change is one of the highest-risk activities in any injection molding, stamping, or die casting plant. Operators work next to multi-tonne molds suspended above the platen, around hot surfaces, and around hydraulic and electrical systems that are normally under interlock. Most reportable injuries on a molding floor — pinch points, dropped molds, hand crush — happen during the change-over window, not during normal production cycles.
This article documents the standard operating procedure (SOP) KINGHOU recommends for plants running quick mold change systems. It is the same procedure used during operator training and 30-day handover support after a clamp or cart installation. The structure follows ISO 12100 risk-assessment principles and is compatible with most plant EHS frameworks.
The Risk Profile of a Mold Change
Before the SOP, it helps to enumerate what actually goes wrong on a mold change. Across the projects KINGHOU has supported, the recurring incident categories are:
- Hand crush at clamp engagement. Operator fingers between mold face and clamp arm during hydraulic engagement.
- Mold drop. Sling failure, off-center lift, or premature release while transporting between rack and press.
- Burn injuries. Contact with hot platen face on die casting and high-temperature injection lines.
- Hydraulic line failure. Disconnecting under pressure, or accidentally pressurising a disconnected line.
- Press unintentional cycle. Press control not properly locked out during change, accidental hand-control activation.
The SOP below is structured to eliminate each of these. Quick mold change hardware reduces the exposure window (faster change = less time at risk), but the SOP is what removes the residual risk inside that window.
The KINGHOU Standard SOP — 12 Steps
Pre-Change (Steps 1–3)
- Step 1 — Production stop and platen cool. Last cycle complete. For die casting and high-temperature injection lines, allow platen to cool to safe handling temperature (target under 60°C). Confirm with infrared thermometer.
- Step 2 — Press lockout / tagout (LOTO). Press control to manual mode. Hydraulic main pump off. Electrical isolator at press disconnect, locked with operator personal lock and tagged.
- Step 3 — Mold release confirmation. Visual confirmation that the existing mold is no longer under clamp pressure. Pressure gauge reads zero.
Mold Removal (Steps 4–6)
- Step 4 — Quick clamp release. HPU activated for release cycle only. Clamps retract and disengage from mold. Operator stays clear of clamp arm path during release.
- Step 5 — Mold transport to cart or crane. If using mold change cart: cart aligns with bolster, mold rolls onto cart at floor level. If using crane: certified slings rigged to mold lifting eyes, lift coordinated with spotter, cordoned floor area.
- Step 6 — Mold to storage. Cart transports to die rack, or crane sets down at staging area. Verify mold seated and stable before disconnecting.
New Mold Installation (Steps 7–9)
- Step 7 — Incoming mold inspection. Visual check of mold faces, clamp slots, and lifting eyes. Reject mold if visible damage to clamp interface.
- Step 8 — Mold transport to press. Reverse of Step 5. Cart presents mold at press centerline; operator confirms alignment before release of cart locking.
- Step 9 — Hydraulic clamp engagement. Operator stands clear of clamp arm zone. HPU activated for engagement cycle. Pressure builds to spec target. Sensor on each clamp confirms engagement.
Re-Cycle Validation (Steps 10–12)
- Step 10 — Clamp force verification. Pressure gauge reads target value (±2% tolerance). Each clamp sensor confirms green-state engagement on the control panel.
- Step 11 — LOTO removal in correct sequence. Electrical isolator energised, hydraulic pump on, press control to auto mode — only after all clamp sensors confirm green.
- Step 12 — First-cycle dry test. Press cycle without injection (or without metal in die casting) to confirm clamp holds under cycle force. Confirm no hydraulic leaks, no clamp slip, no abnormal sound. Then resume normal production.
Personal Protective Equipment Required
- Steel-toe safety boots
- Cut-resistant gloves (Level A4 or higher)
- Safety glasses
- Hard hat (during overhead crane involvement)
- Heat-resistant gloves (die casting and high-temperature injection only)
- High-visibility vest in shared traffic areas
Two-Person Rule
For dies above 2 tonnes, KINGHOU recommends a two-person team for the change-over: one operator at the press handling clamp engagement and inspection, one operator handling cart or crane transport. The two should never share the cart-press transfer zone simultaneously. The operator at the press is responsible for visual confirmation that the transport operator is clear before clamp engagement begins.
Documentation and Audit Trail
For automotive Tier 1 and aerospace certified plants, the change-over should produce an audit log capturing:
- Operator IDs (both operators if two-person rule applied)
- Mold IDs (out and in)
- Clamp engagement pressure for each clamp
- Time stamps for LOTO application and removal
- First-cycle dry test result
The KINGHOU control panel logs all of these automatically when the press cycle interlock is wired in during installation. The data exports as CSV for plant EHS records.
Conclusion
A quick mold change system reduces the exposure window — but the residual risk inside that window only goes to zero with a documented SOP, trained operators, and audit-grade interlock data. The 12-step procedure above is the baseline. Plants with insurance audit obligations or aerospace / automotive certification typically extend it with additional sign-off steps, but the core structure does not change.
Send us your machine tonnage and platen size. KINGHOU will recommend a suitable quick mold change solution — including operator SOP and 30-day on-site training. Reach the engineering team via the contact form, by WhatsApp at +86 18051902698, or by email to kh020@jskinghou.com. Preliminary scope and ballpark quote typically returns within 24 to 48 hours.
